1. Field of the Invention
The present invention relates to an active matrix type display device, and more particularly to an active matrix type display device and a manufacturing method thereof in which, in forming pixels having thin film transistors (TFT) in a matrix array on an insulation substrate which is constituted of a bendable substrate such as a substrate which forms an insulation film on a glass substrate, a plastic sheet (a PES (Polyethersulfone) film or the like) or a steel foil, the display device exhibits the sufficient resistance against electrostatic stress, enables sufficient repair with high reliability using repair lines even when a signal line is disconnected, and realizes light-weighted and compact mounting in combination with chip-on-glass (COG) mounting.
2. Description of the Related Art
Hereinafter, as a display panel which constitutes an active matrix type display device, the explanation is made using a liquid crystal panel as an example. FIG. 24 is a schematic plan view of a TFT substrate of the liquid crystal panel. On the TFT substrate 1, gate signal lines 30 and drain signal lines 40 are formed. On an upper side of the drawing shown in FIG. 24, extension lines 41 which extend from the drain signal lines 40 cross a repair line 43 by way of an insulation film. On a lower side of the drawing shown in FIG. 24, conventional repair lines 400 cross lead lines 402 which extend from the drain signal lines 40 by way of an insulation film. On a peripheral portion of the substrate 1, tape carrier packages (TCP) 410 on which drive ICs are mounted are electrically connected with the gate signal lines 30 and the drain signal lines 40. Further, a vertical scanning circuit, a video signal drive circuit, a power source circuit and a signal conversion circuit which are usually constituted of a printed circuit board 430 convert various signals from a host computer and supply the signals to the above-mentioned substrate.
Conventionally, when a disconnection defective portion 22 occurs in the midst of the signal line, lines arranged on different layers are electrically connected with each other using laser beams. In the drawing, laser beams are radiated once or several times to two portions indicated as portions 26 arranged on an upper side and a lower side of the substrate thus ensuring the electrical connection between the repair line and the signal line.
A signal supply path 91 after repairing allows a drive signal from the TCP 410 to turn around a connection terminal (not shown in the drawing) with the TCP line, the lead line 402 of the signal line, the portion 26 at which the lines arranged on different layers are electrically connected with each other by laser beams, the repair line 400, a connection terminal portion (not shown in the drawing) of the repair line, the repair line 401 in the inside of the TCP, a repair line 401 in the inside of the video signal drive circuit, a flexible printed circuit board (FPC board) 420 for line connection, a repair line 401 in the inside of the vertical scanning circuit line, a FPC 420 for line connection, the repair line 43, the portion 26, and the line 41 which extends from the drain signal line on the substrate and hence, the drive signal is supplied to the upper-side signal lines 40 from the disconnection defective portion 22.
Further, short-circuiting lines for static electricity which are provided for short-circuiting the plurality of gate signal lines 30 and the plurality of drain signal lines 40 with each other are cut and removed from the substrate in the course of manufacturing steps.
Further, FIG. 25 is an explanatory view showing the cutting of the substrate of the conventional liquid crystal panel. As shown in FIG. 25, in the conventional liquid crystal panel, to electrically separate the short-circuiting line 7 for static electricity from the gate signal lines 30 and the drain signal lines 40, scribe lines 8 are formed at many portions and, thereafter, an outer peripheral portion of the substrate (a substrate discarding portion) 600 is cut and removed after passing through a large number of steps such as reversing and transfer of the substrate, cutting of the substrate, horizontal parallel transfer, formation of the scribe lines, reversing and transfer, and cutting of the substrate. Here, numeral 500 indicates a TFT array portion (pixel matrix portion, a display region). As documents which disclose this type of related art, Japanese Patent No. 3167633, Japanese Patent No. 3315834 and JP-A-9-244048 are named.